1
2Find file types by using a modified "magic" file
3
4Based on file v3.22 by Ian F. Darwin (see libfile/LEGAL.NOTICE and
5libfile/README.dist - File v3.22 can be found at many archive sites)
6
7For each entry in the magic file, the "message" for the initial offset MUST
8be 4 characters for the CREATOR and 4 characters for the TYPE - white space is
9optional between them. Any other characters on this line are ignored.
10Continuation lines (starting with a '>') are also ignored i.e. only the initial
11offset lines are used.
12
13e.g magic entry for a GIF file:
14
15# off	type		test		message
16#
17# GIF image
180       string          GIF8            8BIM GIFf
19>4      string          7a              \b, version 8%s,
20>4      string          9a              \b, version 8%s,
21>6      leshort         >0              %hd x
22>8      leshort         >0              %hd,
23#>10    byte            &0x80           color mapped,
24#>10    byte&0x07       =0x00           2 colors
25#>10    byte&0x07       =0x01           4 colors
26#>10    byte&0x07       =0x02           8 colors
27#>10    byte&0x07       =0x03           16 colors
28#>10    byte&0x07       =0x04           32 colors
29#>10    byte&0x07       =0x05           64 colors
30#>10    byte&0x07       =0x06           128 colors
31#>10    byte&0x07       =0x07           256 colors
32
33Just the "8BIM" "GIFf" will be used whatever the type of GIF file it is.
34The continuation lines are used by the "file" command, but ignored by
35mkhybrid. They could be left out completely.
36
37The complete format of the magic file is given in the magic man page (magic.5).
38
39See the file "magic" for other examples
40
41Use with the -magic magic_file option, where magic_file is a file
42described above.
43
44The magic file can be used with the mapping file (option -map) - the order
45these options appear on the command line is important.  mkhybrid will try to
46detect if the file is one of the Unix/Mac files (e.g. a CAP or Netatalk
47file) first. If that fails, it will then use the magic and/or mapping
48file e.g:
49
50mkhybrid -o output.raw -map mapping -magic magic src_dir
51
52The above will check filename extensions first, if that fails to set the
53CREATOR/TYPE, the magic file will be used. To check the magic file
54before the filename extensions, use:
55
56mkhybrid -o output.raw -magic magic -map mapping src_dir
57
58
59Using just a magic file - filename extensions will not be checked e.g:
60
61mkhybrid -o output.raw -magic magic src_dir
62
63For the magic method to work, each file must be opened and read twice
64(once to find it's CREATOR/TYPE, and a second time to actually copy the
65file to the CD image). Therefore the -magic option may significantly
66increase processing time.
67
68If a file's CREATOR/TYPE is not set via the magic and mapping matches,
69then the file is given the default CREATOR/TYPE.
70